Medical instrument

ABSTRACT

A medical instrument includes a housing, a stylet having a portion in the housing, a cannula coaxially receiving the stylet and having a portion in the housing, and a member slidably coupled to the housing. The stylet and the cannula are movable between an extended position and a retracted position. The member is configured with first and second bars to move the stylet and the cannula from their extended positions to their retracted positions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of and claims priority toU.S. application Ser. No. 12/266,452, filed Nov. 6, 2008, which is acontinuation application of and claims priority to U.S. application Ser.No. 11/325,837, filed Jan. 4, 2006, which is a continuation applicationof and claims priority to U.S. application Ser. No. 10/300,512, filedNov. 20, 2002, the entire contents of all of which are hereby fullyincorporated by reference.

TECHNICAL FIELD

This invention relates to medical instruments.

BACKGROUND

A biopsy needle instrument can be used to obtain a tissue specimen formicroscopic examination, e.g., to determine malignancy, while preferablysubjecting the patient to the least trauma. In some embodiments, theinstrument has of a long, thin probe, called a stylet, within aclose-fitting hollow needle, called a cannula. The stylet has a notchinto which tissue can prolapse when the stylet enters the tissue.

During use, a firing device first projects the stylet into tissue,followed immediately by the cannula. As the cannula slides over thestylet, the cannula severs from the surrounding mass tissue that hasprolapsed into the notch of the stylet, and captures the prolapsedtissue as a specimen within the notch. The instrument can then bewithdrawn and the piece of tissue removed from the stylet.

SUMMARY

In one aspect, the invention features a medical instrument that includesa housing, a stylet, a cannula, and a member (e.g., a cocking member).The stylet is movable between an extended position and a retractedposition. The cannula coaxially receives the stylet and is movablebetween its extended position and retracted position. The member iscoupled, e.g., mounted on or connected directly or indirectly, to thehousing, and is capable of moving the stylet from the extended positionto the retracted position, and when separately engaged, moving thecannula from the extended position to the retracted position. The membercan include a button, and the member can be engaged by a user's hand,e.g., palm and/or finger(s).

Embodiments of the aspect of the invention may include one or more ofthe features described above and below, in any combination.

In another aspect, the invention features a medical instrument thatincludes a housing, a stylet, a cannula, and a member, e.g., a cockingmember. The stylet is movable between an extended position and aretracted position. The cannula coaxially receives the stylet and ismovable between its extended position and retracted position. The memberis slidably coupled to the housing, and is configured such that when auser engages the member (e.g., two times), the cannula is moved from anextended position to a retracted position and the stylet is moved froman extended position to a retracted position, in a sequential manner.The member can be configured such that the cannula is moved from anextended position to a retracted position when a user engages the membera first time, and the stylet is moved from an extended position to aretracted position when a user engages the member a second time. Themember can also be configured such that the stylet is moved from anextended position to a retracted position when a user engages the membera first time, and the cannula is moved from an extended position to aretracted position when a user engages the member a second time.

In some embodiments, the instrument can further include a cannula blockthat includes at least one (e.g., two, three, or more) retentiveportion(s) capable of holding the cannula in the retracted position. Thecannula block is attached to a proximal end of the cannula. Theinstrument can also include a cannula block receiver which includes atleast one (e.g., two, three or more) locking surfaces, wherein thelocking surface(s) engages, e.g., locks into, the retentive portion(s)of the cannula block when the cannula is in the retracted position.

The instrument can also include a primary bar coupled, e.g., attached bya linkage, to the member. The primary bar is engageable with the cannulablock to move the cannula block and cannula to the retracted position.In some embodiments, the primary bar is capable of being in a firstposition in which the primary bar is engageable with the cannula blockto move the cannula block and cannula to the retracted position withoutmoving the stylet block, and in a second position in which the primarybar is engageable with a secondary bar to move the stylet block andstylet to the retracted position.

In some embodiments, the instrument can include a stylet block attachedto the stylet, and a stylet block receiver. The stylet block receiverand stylet block can engage when the stylet is in the retractedposition. The instrument can include a secondary bar engagable with thestylet block and adapted to move the stylet block and stylet to theretracted position. Further, the instrument can include a first triggerengageable with the stylet block receiver to release the stylet from theretracted position. The first trigger can be located on the housing,e.g., the proximal end of the housing, and can pivotally move the styletblock receiver to disengage the stylet block receiver from the styletblock. In some embodiments, the instrument can include a second triggeralso being configured to release the stylet from the retracted position.

In other embodiments, the instrument can include an indicator thatindicates when the stylet is in the second retracted position.

In another aspect, the invention features a medical instrument thatincludes a housing, a stylet having a portion in the housing and movablebetween an extended position and a retracted position, a stylet blockattached to a proximal end of the stylet, a cannula coaxially receivingthe stylet and having a portion in the housing, the cannula beingmovable between an extended position and a retracted position, a cannulablock attached to a proximal end of the cannula, a member slidablycoupled to the housing, a secondary bar within the housing and capableof moving the stylet block from an extended position to a retractedposition, and a primary bar within the housing and coupled to themember. The primary bar is capable of being in a first position in whichthe primary bar is engageable with the cannula block to move the cannulablock and cannula to the retracted position without moving the styletblock, and in a second position in which the primary bar is engageablewith the secondary bar to move the stylet block and stylet to theretracted position.

In some embodiments, the medical instrument can include a triggermechanism that includes a first trigger element that has a firsttrigger, and a second trigger element that has a second trigger, whereinthe second trigger element is configured to retain the stylet block andstylet in the retracted position, and wherein the first and secondtrigger elements are engagable such that the stylet block and stylet arereleased from the retracted position when the first or second trigger isengaged.

In still another aspect, the invention features a medical instrumentthat includes a housing, a stylet, a cannula, and a member, e.g., acocking member, and an indicator. The stylet is movable between anextended position and a retracted position. The cannula coaxiallyreceives the stylet and is movable between its extended position andretracted position. The member is slidably coupled to the housing, andis configured such that when a user engages the member (e.g., twotimes), the cannula is moved from an extended position to a retractedposition and the stylet is moved from an extended position to aretracted position, in a sequential manner. The indicator is associatedwith the housing, and provides a visual indication of the position ofthe stylet by a change, e.g., in color or symbol.

In another aspect, the invention features a medical instrument thatincludes a housing, a stylet, a cannula, and a member slidably coupledto the housing. The stylet is movable between an extended position and aretracted position. The cannula coaxially receives the stylet and ismovable between its extended position and retracted position. The memberis slidably coupled to the housing, and is configured to move thecannula from the extended position to the retracted position and, duringa separate engagement by a user, to move the stylet from the extendedposition to the retracted position.

In yet another aspect, the present invention features a method of takinga biopsy sample from a patient. The method includes providing a medicalinstrument of the present invention, engaging the member a firstinstance to move the cannula from an extended position to a retractedposition, engaging the member a second instance to move the stylet froman extended position to a refracted position, placing a distal end ofthe cannula against a patient, and activating, e.g., firing, the medicalinstrument. The instrument can be engaged using at least one trigger torelease the stylet from the second retracted position. The inventionalso features using the medical instrument on a patient, e.g., a human,in a medical procedure.

Embodiments may have one or more of the following advantages. Theinstrument can be relatively easy to load prior to firing theinstrument. The member of the instrument provides good mechanicaladvantage and is used to load the stylet and the cannula with the samemotion. The instrument can include two trigger mechanisms, whichenhances the versatility and convenience of the instrument. For example,depending on a target site and/or preference of a user, a radiologistcan prefer to use a side trigger, while a urologist can prefer the reartrigger.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the present invention, suitable methods andmaterials are described below. All publications, patent applications,patents, and other references mentioned herein are incorporated byreference in their entirety. In case of conflict, the presentspecification, including definitions, will control. In addition, thematerials, methods, and examples are illustrative only and not intendedto be limiting.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an embodiment of a biopsy instrument.

FIG. 2 is an exploded, perspective view of the biopsy instrument of FIG.1.

FIGS. 3A-D illustrate the biopsy instrument of FIG. 1 at various stagesof operation.

FIGS. 4A-4B is an enlarged view of an embodiment of the presentinvention.

FIGS. 5A-5C illustrate an alternative embodiment of the biopsyinstrument at various stages of operation.

DETAILED DESCRIPTION

Referring to FIGS. 1, 2, and 3A, a biopsy instrument 1 includes ahousing 2, a stylet 55, a cannula 21, a member 7 slidably coupled to thehousing 2, a side trigger 35, and a rear trigger 36. Housing 2 includesa top shell 3 and a bottom shell 33 (as shown in Figures) that arebonded together. Stylet 55 and cannula 21 have portions located withinhousing 2 and are configured to be axially movable relative to eachother, between retracted positions and extended positions. As shown inFIG. 3A, stylet 55 and cannula 21 are in their extended positions.During use, stylet 55 and cannula 21 are loaded or cocked to theirretracted positions, ready to be triggered. When stylet 55 and cannula21 are triggered, they rapidly move distally to their extendedpositions, e.g., to collect a tissue specimen that has prolapsed into anotch (not shown) located near the distal end of stylet 55. Member 7 isconnected to primary bar attachment element 9 of the primary bar 8 via alinkage 38. Overall, member 7 and primary bar 8 are parts of a mechanismthat is used to load both stylet 55 and cannula 21 to their retractedpositions. Specifically, member 7 and primary bar 8 together movecannula 21 to its retracted position and member 7, primary bar 8, andsecondary bar 13 together move stylet 55 to its retracted position.After stylet 55 and cannula 21 are loaded, either side trigger 35 orrear trigger 36 can be used to release the stylet and the cannula totheir extended positions.

Referring to FIGS. 2 and 3A, cannula 21 is generally a hollow sheath,e.g., made of stainless steel, that receives stylet 55, which can alsobe made of stainless steel. At its distal end 39, cannula 21 isconfigured to sever tissue that has prolapsed into a notch (not shown)formed with at the distal end of stylet 55. Cannula 21 extends intohousing 2 wherein the cannula is attached to an axially movable (arrowA) cannula block 22.

Cannula block 22 includes a cannula block hook 23, which extends throughprimary bar elongate perforation 10 and secondary bar elongateperforation 14 when instrument 1 is assembled. Cannula block hook 23 isengaged at its rear surface 40 by primary bar attachment element 9during use (described below). Cannula block first raised portion 23 alsoengages primary bar 8 at its proximal end 20 of primary bar 8 (describedbelow). Cannula block 22 also includes an orifice 41 adapted to receivea first compression spring 24, e.g., a stainless steel spring, e.g.,having a spring rate of 9.77 lb/in, and two cannula block retentiveportions 42. First compression spring 24 engages cannula block 22 andbiases cannula block 22 distally. Cannula block retentive portions 42are raised portions on either side of cannula block 22, and are adaptedto engage cannula block receiver 31 and cannula block receiver lockingsurfaces 32.

Cannula block receiver 31 can be, e.g., a prong-shaped element havingtwo arms 43 adapted to receive cannula block 22. Cannula block receiveris pivotally attached to bottom shell 33 by linkages 44, which allowcannula block receiver 31 to pivot (arrow B). Cannula block receiveralso includes cannula block receiver locking surfaces 32, which are,e.g., raised and angled surfaces adapted to guide cannula block 22 intocannula block receiver 31, and to engage cannula block retentiveportions 42.

Stylet 55 is slidably and coaxially located in cannula 21. Stylet 55 hasa distal end (not shown) configured to penetrate tissue and a notch (notshown) for collecting a tissue sample. Examples of suitable stylet 55and cannula 21 configurations are exemplified by the ASAP™ AutomatedBiopsy System having a Delta Cut® needle or a Channel Cut® needle(available from Boston Scientific Corp., Natick, Mass.), and describedin Chu, U.S. Pat. No. 5,989,196, hereby incorporated by reference. Fromdistal end (not shown), stylet 55 extends into housing 2 where stylet 55is attached to an axially movable stylet block 26.

Stylet block 26 includes two arms 37, which are adapted to contactcannula block receiver 31 around stop block 60A of bottom shell 33during firing of the instrument (described below). Stylet block 26 alsoincludes a stylet block raised portion 27, which is adapted to bereceived between the arms 47 of secondary bar 13. Stylet block 26 alsoincludes an orifice 45 adapted to receive a second compression spring25, e.g., a stainless steel spring having a spring rate of 9.77 lb/in,and two stylet block retentive portions 53, e.g., notches adapted to bereceived by stylet block receiver 30 and stylet block locking surfaces49.

Stylet block receiver 30 is pivotally attached to bottom shell 33 bylinkages (not shown), which allow stylet block receiver 30 to pivot(arrow C). Stylet block receiver 30 is a generally L-shaped element thatincludes a rear surface 50 that can contact rear trigger 36 on triggerbar 34. Stylet block receiver 30 also includes stylet block lockingsurfaces 49, which are, e.g., raised and angled surfaces adapted toguide stylet block 26 into stylet block receiver 30 and to engage styletblock retentive portions 53. Stylet block receiver can also include tworaised surfaces 56 on rear surface 50 of stylet block receiver 30, whichcan be configured to receive rear trigger 36.

Trigger bar 34 is a generally elongate element having a rear trigger 36at its proximal end 51 and a side trigger 35 near its distal end 52.Rear trigger 36 is, e.g., a portion of trigger bar 34 formed in theshape of tab or button. Rear trigger 36 is adapted to contact rearsurface 50 of stylet block receiver 30. Side trigger 35 can also be aportion of trigger bar 34 formed in the shape of tab or button.

Bottom shell 33 of housing 2 includes stop block 60A, which is situatedproximally to cannula block receiver. Bottom shell 33 can also includefirst 73 and second 74 walls formed therein, between which stylet block26 and/or cannula block 22 move during operation of instrument 1. FIGS.4A and 4B illustrate one embodiment of stop block 60A. Referring to FIG.4A, stop block 60A can be formed such that one side (e.g., 60B) of stopblock 60A is slightly thicker, e.g., about ⅛^(th) of an inch thicker,than the other side (e.g., 60C), of stop block 60A. In such anembodiment, when stylet block 26 contacts stop block 60A (see FIG. 4B),stylet block 26 rotates slightly to cause friction between stylet 24 andcannula 21, decreasing or preventing recoil of stylet block 26 duringfiring of the instrument (described below). Accordingly, wall 73 caninclude a gap 75, which allows stylet block 26 to rotate between firstwall 73 and second wall 74 (see FIG. 4B).

Bottom shell 33 includes a first recessed portion 48 or perforation atits proximal end 58 adapted to receive rear trigger 36, and a secondrecessed portion 54 or perforation adapted to receive side trigger 35.Bottom shell 33 can also include raised portions 57 at distal end 63 ofthe bottom shell. In some embodiments of the present invention, theseraised portions can be used for joining primary bar 8 to bottom shell 33by at least one (e.g., two) spring(s) (not shown). Specifically,spring(s) (not shown) can be connected to raised portions 57 on bottomshell 33 at one end, with the other end of the spring(s) (not shown)being attached to optional raised portions 59 on primary bar 8. Theinclusion of springs connecting primary bar 8 and bottom shell 33results in the primary bar 8 being biased toward the distal end 62 oftop shell 3.

Top shell 3 of housing 2 includes a recessed portion 4 adapted to allowmember 7 to slide longitudinally (arrow D) within the recessed portion.Member 7 can take any shape, e.g., a formed button, tab, or finger grip.Top shell 3 also includes elongate perforation 5, through which member 7and primary bar attachment element 9 are connected by linkage 38. Topshell 3 can also include at least one perforation, e.g., window 6, whichcan be utilized as an indicator (described below).

Primary bar 8 includes primary bar attachment element 9, which serves,in part, to attach primary bar 8 to member 7 via linkage 38. Primary bar8 also has a surface 12 that can contact rear surface 40 of cannulablock hook 23. Primary bar 8 also includes two recessed portions 11 atits distal end 16, which are adapted to engage secondary bar raisedportions 15 during use of the instrument. Primary bar 8 also includes anelongate perforation 10 through which cannula block hook 23 extends.

Secondary bar 13 includes secondary bar raised portions 15, adapted tobe received by primary bar recessed portions 11. At proximal end 46,secondary bar 13 includes two arms 47 adapted to engage and receivestylet block raised portion 27 during use of the instrument. Secondarybar also includes also includes an elongate perforation 14 (throughwhich cannula block hook 23 extends), and secondary bar stops 17.Secondary bar also includes guide surfaces 19 adapted to receive andguide primary bar in a slidable manner during use of the instrument.

In some embodiments of the present invention, instrument 1 includes afirst 29 and/or a second 28 O-ring, which can act to absorb shock, thusaffording more comfort to the user (e.g., by decreasing vibration) anddecreasing sound that emanates from the instrument during use.

In some embodiments, window 6 in top shell 3 can act as a visualindicator (or as part of a visual indication system), which signals whenstylet 55 is in its retracted position (loaded position). The indicationsystem can include one or more perforations (e.g., window 6 in top shell4) formed in housing 2 that allow a user to detect a change in theposition of stylet block 26. For example, perforation(s) can be formedon housing 2 such that stylet block raised portion 27 covers thewindow(s) when the stylet block 26 is in its extended position. Whenstylet block 26 is retracted, stylet block raised portion 27 slides awayfrom window(s) and uncovers interior portions of instrument 1. Theinterior portions can be colored, e.g., red, for enhanced visibility. Inother embodiments, perforation 6 can be aligned with stylet block raisedportion 27 which has a first color, e.g., red, and the interior portionscan have a second color, e.g., green. When stylet block 52 is moved fromits extended position to its retracted position, the color visiblethrough window(s) changes from the second color to the first color toindicate that instrument 1 is loaded. Alternatively or in addition,instrument 1 can include a perforation(s) in housing 2 aligned withcannula block 23 to indicate the position of the cannula block. Forexample, cannula block 23 can be formed with portions with differentcolors as described above.

FIGS. 3A-3D illustrate a sequence of the operation of instrument 1.Referring to FIG. 3A, instrument 1 is in its rest position, e.g., astaken out of its packaging. Cannula block 22 and stylet block 26 are attheir most distal, extended positions. Member 7 and both primary 8 andsecondary 13 bars are in a distal position.

To load or move cannula block 22 and stylet block 26 to their retractedpositions, member 7 is engaged, e.g., moved (cocked) toward the proximalend of instrument 1, two times. Referring to FIG. 3B, when member 7 isengaged the first time, primary bar 8 contacts rear surface 40 ofcannula block hook 23, and both primary bar 8 and cannula block 22 aremoved in a proximal direction. As a result, cannula block 22 and cannula21 are pushed proximally until cannula block retentive portions 42engage cannula block receiver locking surfaces 32. As cannula blockreceiver 31 receives cannula block 22, cannula block receiver 31 rotates(arrow B) to allow cannula block retentive portions 42 to engage cannulablock receiver locking surfaces 32. Cannula block receiver arms 43 pressagainst top shell 3 to bias the rotation of cannula block receiver 31 toa clockwise (arrow B) direction. Once cannula block receiver lockingsurfaces engage, e.g., lock into, cannula block retentive portions 42,the cannula block 22 and cannula 21 remain in their retracted positions(FIG. 3B). In this position, first compression spring 24 is compressedbetween cannula block 22 and stop block 60A in bottom shell 33. Member 7is then released by the user and allowed to return to its distalposition, e.g., aided by a spring (not shown).

When member 7 is engaged the first time, primary bar 8 is in a firstposition and not aligned with stops 17 on secondary bar 14. As a result,during the first actuation of member 7, primary bar can slide over stops17. However, as member 7 and primary bar 8 return to their distalposition after the first actuation, cannula block hook 23 engagessurface 61 at proximal end 20 of primary bar 8. When cannula block hook23 engages surface 61, primary bar rotates or flexes slightly to asecond position, such that proximal end 20 of primary bar 8 aligns withstops 17 of secondary bar 13. As a result, member 7, primary 8 andsecondary 13 bars all move together when member 7 is engaged a secondtime. Specifically, when member 7 is engaged a second time, primary bar8 contacts rear surface 40 of cannula block hook 23, proximal end 20 ofprimary bar 8 contacts secondary bar stops 17, and secondary bar 13 armsengage stylet block raised portion 27. As a result, stylet block 26 andstylet 55 are pushed proximally until stylet block retentive portions 53engage stylet block receiver 30 and stylet block receiver lockingsurfaces 49. Once stylet block receiver locking surfaces 49 engage,e.g., lock into, stylet block receiver locking surfaces 49, stylet block26 and stylet 55 remain in their retracted positions (FIG. 3C). In thisposition, second compression spring 25 is compressed between styletblock 26 and stylet block receiver 30. Referring to FIG. 3C, bothcannula 21 and stylet 55 are fully cocked and prepared for use. Cannulablock 22 and stylet block 26 are at their most proximal, retractedpositions. Instrument 1 cocked and ready to be triggered or fired.

To fire instrument 1, distal end of stylet (not shown) is placedadjacent to a target area, and either side trigger 35 or rear trigger 36is engaged. To engage rear trigger 36, the rear trigger is pusheddistally, e.g., using an index finger, which causes rear trigger 36 topush rear surface 50 of stylet block receiver 30. As a result, styletblock receiver 30 pivots (arrow C) to disengage stylet block retentiveportions 53 from stylet block receiver locking surfaces 49. Upondisengagement, stylet block 26 and stylet 55 are propelled distally bythe spring force of second compression spring 25, which allows stylet 55to penetrate the targeted area. Stylet block 26 then strikes cannulablock receiver 31 (FIG. 3D), causing it to pivot (arrow B) to disengagecannula block retentive portions 42 from cannula block receiver lockingsurfaces 32. Upon disengagement, cannula block 22 and cannula 21 arepropelled distally by the spring force of second compression spring 24,which allows cannula 21 to slide over stylet 55 and to sever a specimenthat has prolapsed into notch (not shown) within stylet 55.

Instrument 1 can then be withdrawn. The specimen can be removed fromstylet notch (not shown) by engaging member 7 once to retract cannula 21and expose stylet 55. The specimen can be placed on a slide or in apreservative solution. If desired, member 7 can be engaged to retractand load stylet 55 to collect another specimen.

Side trigger 35 is engaged by pushing the side trigger 35 distally,e.g., using an index finger, which causes trigger bar 34 to movedistally as well. Accordingly, rear trigger 36 also moves distally,which causes instrument 1 to fire as described above.

FIGS. 5A-5C illustrate an alternative embodiment of the presentinvention, wherein biopsy instrument 1 includes an alternative firingmechanism. Referring to FIG. 5A, wherein instrument 1 is in a restingposition, trigger bar 34 is replaced with a firing mechanism thatincludes rear trigger element 64 and side trigger element 65. Reartrigger element 64 includes rear trigger 36 and rear trigger elementangled end 72A. Rear trigger element angled end 72A includes an angledsurface 72B. Angled surface 72B is adapted to contact another angledsurface, angled surface 71B, of side trigger element 65 at junction 70.Side trigger element 65 includes side trigger 35 and side triggerelement angled end 71A. Side trigger element angled end 71A includesangled surface 71B. Angled surface 71B is adapted to contact angledsurface 72B at junction 70. Side trigger element 65 also includesretentive portion 68, which is adapted to contact and retain styletblock 25 in a cocked position when biopsy instrument 1 is loaded (seeFIG. 5B). In this embodiment, stylet block 26 includes stylet blocknotch 69, which is engaged by retentive portion 68 when biopsyinstrument 1 is at rest (e.g., after firing). Retentive portion 68 islocated next to angled surface 71B at side trigger element angled end71A. Side trigger element 65 also includes side trigger element pivot 66and leaf spring end 67. Side trigger element can be pivotally connectedto bottom shell 33.

In this alternative embodiment, the instrument 1 is cocked in a mannersimilar to that described above, i.e., member 7 is engaged two times.Referring to FIG. 5C (wherein instrument 1 is illustrated in the processof firing), instrument 1 can be fired using either side trigger 35 orrear trigger 36. To engage rear trigger 36, rear trigger is pushed(leftward in FIG. 5C), e.g., using an index finger, which causes reartrigger element 64 to move in the same direction (leftward in FIG. 5C).This motion causes angled surface 72B to slide against angled surface71B at junction 70, causing side trigger element 65 and retentiveportion 68 to rotate about pivot 66, disengaging retentive portion 68from stylet block 26. Stylet 55 and cannula 21 are then discharged andpropelled forward as described above.

To fire the instrument using side trigger 35, the side trigger is pushed(upward in FIG. 5C) e.g., using an index finger, which causes sidetrigger element angled end 71B and retentive portion 68 to rotate aboutpivot 66, disengaging retentive portion 68 from stylet block 26. Theinstrument then discharges as described above. Leaf spring end 67 biasesretentive element 68 to a resting position (see FIGS. 5A and 5B).

In some embodiments, housing 2 and/or member 7 can each be made ofdifferent materials, e.g., to enhance the grip or “feel” of instrument1. For example, housing 2 and/or member 7 can be formed of materialswith different hardness, e.g., a core of relatively hard material and anouter layer of relatively soft material. The outer layer can be a foamymaterial, such as a urethane, to enhance the grip and/or to absorbvibrations from the firing of instrument 1. Each of housing 2 and/ormember 7 can be formed with two or more different materials.

The components of instrument 1 described above can be formed byconventional injection molding techniques, e.g., of polycarbonate and/orABS. Stylet 55, cannula 21, first 24 and second 25 compression springscan be formed of stainless steel.

The term “patient” includes all animals, human or non-human. Examplesinclude birds, reptiles, amphibians, and mammals, e.g., humans, otherprimates, pigs, rodents such as mice and rats, rabbits, guinea pigs,hamsters, cows, horses, cats, dogs, sheep and goats. Preferred patientsare humans, farm animals, and domestic pets such as cats and dogs.

The biopsy instrument can be used for sampling in any part of a body,e.g., stomach, colon, rectum, mouth/pharynx, esophagus, larynx, liver,pancreas, lung, breast, cervix uteri, corpus uteri, ovary, prostate,testis, bladder, skin, kidney, brain/central nervous system, head, neckand throat, among others.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

What is claimed:
 1. A method of taking a biopsy sample, the methodcomprising: moving a cannula of a medical device from a cannula extendedposition to a cannula retracted position by engaging a member on themedical device a first time; moving a stylet of the medical device froma stylet extended position to a stylet retracted position by engagingthe member on the medical device a second time, wherein engaging themember includes sliding the member along a housing of the medicaldevice; and activating the medical device.
 2. The method of claim 1,wherein engaging the member on the medical device comprises moving themember from a member extended position to a member retracted position.3. The method of claim 2, further comprising returning the member on themedical device from the member retracted position to the member extendedposition by releasing the member on the medical device.
 4. The method ofclaim 1, further comprising moving a primary bar coupled to the memberfrom a first primary bar position in which the primary bar is engageablewith a cannula block to move the cannula block and the cannula to thefirst retracted position without moving the stylet to a second primarybar position in which the primary bar is engageable with a secondary barto move a stylet block and the stylet to the second retracted position.5. The method of claim 4, wherein moving the primary bar between thefirst primary bar position and the second primary bar position comprisesrotating the primary bar.
 6. The method of claim 4, wherein positioningthe cannula in the cannula retracted position moves the primary bar fromthe first primary bar position to the second primary bar position. 7.The method of claim 1, comprising placing a distal end of the cannulaagainst a patient before activating the medical instrument.
 8. Themethod of claim 7, comprising moving a cannula of the medical devicefrom the cannula extended position to the cannula retracted position byengaging the member on the medical device a third time.
 9. The method ofclaim 8, comprising removing the biopsy sample from the stylet.
 10. Themethod of claim 1, wherein activating the medical device comprisesreleasing the stylet from the stylet retracted position using a trigger.11. A method of taking a biopsy sample, the method comprising: moving acannula of a medical device from a cannula extended position to acannula retracted position by engaging a member on the medical device afirst time; wherein positioning the cannula in the first retractedposition moves a primary bar from a first primary bar position in whichthe primary bar is engageable with a cannula block to move the cannulablock and the cannula to the first retracted position without moving astylet, to a second primary bar position in which the primary bar isengageable with a secondary bar to move a stylet block and the stylet toa second retracted position; moving the stylet of the medical devicefrom a stylet extended position to a stylet retracted position byengaging the member on the medical device a second time; and activatingthe medical instrument; wherein engaging the member on the medicaldevice comprises sliding the member along a housing of the medicaldevice.
 12. The method of claim 11, wherein engaging the member on themedical device comprises moving the member from a member extendedposition to a member retracted position.
 13. The method of claim 12,comprising returning the member on the medical device from the memberretracted position to the member extended position by releasing themember on the medical device.
 14. The method of claim 11, wherein movingthe primary bar from the first primary bar position to the secondprimary bar position comprises rotating the primary bar.
 15. The methodof claim 11, comprising placing a distal end of the cannula against apatient before activating the medical instrument.
 16. The method ofclaim 15, comprising moving a cannula of the medical device from thecannula extended position to the cannula retracted position by engagingthe member on the medical device a third time.
 17. The method of claim16, comprising removing the biopsy sample from the stylet.
 18. Themethod of claim 11, wherein activating the medical device comprisesreleasing the stylet from the second retracted position using a trigger.